Currently composite structures containing natural cellulose fibers are used in the automotive industry for package trays, interior door trim, rear window shelves, seat backs, carpet backing, and acoustic insulation. Examples of articles of composite construction are disclosed in U.S. Pat. Nos. 4,474,846, 5,883,025, 6,123,172 and 6,184,272. Other uses for composite structures containing natural cellulose fibers include such articles as flowerpots, moldings, railroad ties, furniture, marine piers, acoustic insulation, packaging and other building and consumer products.
Many of these articles contain natural cellulose fibers or other fibrous components and a polymer component, which may be a polyolefin (polyethylene, polypropylene) or poly vinyl chloride in the form of fibers or flakes. Polypropylene is a polymer component often used in the automotive industry. The conventional method for producing these articles is to mold, using heat and pressure, a natural cellulose fiber/polymer mixture as in the case of wood/polyethylene composites. Another method is to mold a non-woven or multi-layered structure, which contains the natural cellulose fiber and a binder polymer as well as any mineral fillers and colorants, into a desired product. The application of heat and pressure in molding fuses the binder polymer and natural cellulose fiber or other fibrous component of the admixture or non-woven together. A unified composite article is formed with tensile, stiffness, impact and surface properties necessary for the desired end uses. If the binder polymer is used in sufficient quantity the natural cellulose fiber may be completely encapsulated by the polymer. These molded structures may be up to 50 weight percent (weight %) binder polymer.
Changes in environmental regulations are increasing the need for compostable and biodegradable composites. One of the limitations of the articles described above is their lack of biodegradability when composted, which is due to the nature of the binder polymer used. In the past polyethylene and polypropylene, as well as poly vinyl chloride, epoxides and phenolics have been used in this type of natural cellulose fiber composite. In composting environments olefins, poly vinyl chloride, epoxides and phenolics do not biodegrade readily.
Thus, there exists a need in the art for a biodegradable, compostable, moldable composite article having the structural properties of the existing composites that could be disposed of in a conventional composting landfill at the end of its useful life. Additionally, there is an ongoing conservation need to utilize components that are produced from renewable resources. Accordingly, it is to the provision of such that the present invention is directed.